IN THE MEAN EFFECTS OF THE LARGER MAGNETIC DISTURBANCES. 123 
Postscript, May 24th, 1852. 
The interval which has elapsed between the presentation and the printing of this 
paper has enabled me to complete the examination of the disturbances at Toronto 
from the commencement of the observations in 1841, and to subjoin the results. 
The observations were made two-hourly from January 1841 to June 1842 inclusive, 
and hourly from July 1842 to July 1848 inclusive : all those which differed 3 6 or 
upwards from the mean or normal Declination at the same hour in the same month 
have been separated from the others, and constitute the body of disturbed observa- 
tions submitted to examination. It appears desirable to state, in addition to the ratios, 
the numbers and aggregate values of the disturbed observations in each year, dividing 
them into easterly and westerly disturbances : this is done in the following Table : — 
Table XXIII. 
Years. 
Disturbed observations. 
Numbers. 
Aggregate values. 
Easterly. 
Westerly. 
Total. 
Easterly. 
Westerly. 
Total. 
1841. Twelvemonths: observations two-hourly 
282 
288 
570 
1865 
1756 
3615 
1 S 40 / January to June, two-hourly]^ 
\ July to December, hourly J 
327 
279 
606 
1947 
1623 
3570 
1843. Twelve months; hourly 
268 
204 
472 
1515 
1133 
2648 
1844. Ditto Ditto 
327 
269 
596 
2162 
1692 
3854 
1845. Ditto Ditto 
298 
269 
567 
1761 
1544 
3305 
1846. Ditto Ditto 
547 
484 
1031 
3655 
3002 
6657 
1847. Ditto Ditto 
532 
409 
941 
3620 
3804 
7424 
1848. January to June, hourly 
288 
250 
538 
2185 
1609 
3794 
It will be observed that in this Table the values from 1843 to 1847 inclusive, are 
strictly intercomparable, those years being complete years of hourly observation ; 
whereas in 1841 and in part of 1842 the observations were only two-hourly, and in 
1 848 the observations were limited to the first six months. In order therefore to render 
the numbers and aggregate values in Table XXIII. readily comparable by the eye, it 
may be convenient to double those of 1841 and 1848, and to augment those of 1842- 
in the proportion of 4 to 3 : this is done in the following Table : — 
Table XXIV. 
Years. 
Numbers. 
Aggregate values. 
Easterly. 
Westerly. 
Total. 
Easterly. 
Westerly. 
Total. 
1841. 
564 
576 
1140 
3730 
3500 
7230 
1842. 
436 
372 
808 
2596 
2164 
4760 
1843. 
268 
204 
472 
1515 
1133 
2648 
1844. 
327 
269 
596 
2162 
1692 
3854 
1845. 
298 
269 
567 
1761 
1544 
3305 
1846. 
547 
484 
1031 
3655 
3002 
6657 
1847. 
532 
409 
941 
3620 
3804 
7424 
1848. 
576 
500 
1076 
4370 
3217 
7587 
R 2 
